Comparison of the effects of ultrasound toothbrushes with different frequencies on oral hygiene: A randomized-controlled clinical trial

Background The purpose of this study was to examine whether high-frequency ultrasound toothbrushes have different effects on oral hygiene. Methods Fifty first-year dental hygiene students were randomly divided into three groups using ultrasound toothbrushes with different frequencies (1.6, 3.2 and 4.8 MHz) twice a day (3-min sessions) for 8 weeks. Plaque index (PlI) and gingival index (GI) scores were assessed at 4 and 8 weeks. Results Changes in GI scores from baseline to 8 weeks tended to differ among the groups (p = 0.0862). The GI was significantly lower in the 3.2 and 4.8 MHz groups at 8 weeks (3.2 MHz group: p < 0.01, 4.8 MHz group: p < 0.05). At 4 weeks, the GI was significantly lower in the 3.2 MHz group (p < 0.05) and tended to be lower in the 4.8 MHz group (p = 0.07). The PlI was significantly lower in the 3.2 MHz group at 8 weeks (p < 0.01) and tended to be lower in the 1.6 and 4.8 MHz groups (1.6 MHz: p = 0.07, 4.8 MHz: p = 0.05). In addition, the PlI was significantly lower in the 4.8 MHz group at 4 weeks (p < 0.05). No significant differences in the changes in any measurements were observed among the groups. Conclusions The results of this study indicated that ultrasound toothbrushes with different frequencies probably have different effects on oral hygiene. However, it is difficult to conclude strongly that higher frequency ultrasound toothbrushes are more effective as there were some limitations.